Intro paragraph:
First, you need a hook to get us interested. You can have a thought-provoking quote or fact, or even a strong statement, or pose a question to the reader. If you do, at least follow-up with a few sentences to develop/discuss that fact or quote or question. Also, you can start it with a hypothetical scenario, putting the reader in the shoes of the situation. The hook typically takes up the first third of your intro.
Second is the background information - the stuff we need to know to understand this topic you will be discussing. Give us a brief history or understanding of some of the terms you will be using. This takes up another third of the intro.
Next comes a universal statement. This is the sugar to help the medicine of your thesis go down. You need to come up with a statement that even people who might be on the opposite side would agree with. To do this it may be very broad. If my thesis was we should have universal health care, a universal statement would be..."Everyone wants to have the care they need, and would want the same for their friends, families and neighbors."
Finally, one sentence: your thesis. Make sure it is concise and to the point.
Conclusion paragraph:
1) restate your thesis in different words.
2) summarize each of your body paragraphs
3) give the call to action
4) Finale: just like the hook got us interested, the finale needs to be interesting and leave us thinking. Again, this can be a quote, fact, statement, question, or hypothetical scenario. End strong, because this is your last impression.